The present invention relates to a speaker device.
The present application claims priority from Japanese Application No. 2005-373234, the disclosure of which is incorporated herein by reference.
A conventional speaker device comprises: a magnetic circuit containing a permanent magnet; a voice coil freely vibratably disposed within a magnetic gap of the magnetic circuit; a voice coil bobbin wound around by the voice coil; and a conical diaphragm fixed to the voice coil bobbin. When the speaker device is required to generate a large sound pressure, an electric signal having a relatively high level will be caused to flow into the voice coil through a terminal section. At this time, a driving force will be applied to the voice coil bobbin through the voice coil, thereby causing a vibration of a conical diaphragm connected with the voice coil bobbin. As a result, such a driving force will greatly act on a fixing section combining together the voice coil bobbin and the conical diaphragm. Accordingly, if the fixing section does not have an adequate strength, an adhesion exfoliation would occur and thus the fixing section could be broken. Moreover, if a strength is low in a neck portion near the central position of the conical diaphragm, an undesired dividing vibration will occur in the diaphragm, resulting in a deteriorated sound quality in a reproduced sound. To solve this problem, there has been suggested an improved speaker device having an improved strength in the neck portion of a speaker diaphragm. For example, Japanese Unexamined Patent Application Publication No. (Hei) 10-210593 has suggested that an engaging portion formed in the neck portion of the diaphragm be inserted into a slit formed along the circumference of the voice coil bobbin, thereby improving a strength of the neck portion of the diaphragm.
On the other hand, in a conventional speaker device, a notch is formed in the vicinity of a fixing section fixing together the voice coil bobbin and the conical diaphragm, particularly in the neck portion of the diaphragm, while a lead wire is led out from the voice coil through the notch. However, the formation of the notch in the neck portion of the diaphragm could reduce the strength of a part of the diaphragm near the notch. Moreover, when a notch is formed, a distortion could occur in the diaphragm, causing a deterioration in the sound quality of a reproduced sound. Besides, when the foregoing notch is formed, the diaphragm is likely to be broken, making it technically difficult to perform a processing for forming a notch in an injection molded PP (polypropylene) diaphragm or an aramid-containing diaphragm. In addition, with regard to the above-discussed conventional speaker device, it is also technically difficult to perform a processing for forming an engaging portion in the neck portion of a conical PP diaphragm or the like.